mirror of
https://github.com/Z3Prover/z3
synced 2025-04-13 20:38:43 +00:00
dbc299efbb
- share common functionality - rename propagate-bv-bounds-new to propagate-bv-bound2 for now - expose configuration options in bounds propagation
639 lines
20 KiB
C++
639 lines
20 KiB
C++
/*++
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Copyright (c) 2016 Microsoft Corporation
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Module Name:
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bv_bounds_tactic.cpp
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Abstract:
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Contextual bounds simplification tactic.
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Author:
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Nuno Lopes (nlopes) 2016-2-12
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Nikolaj Bjorner (nbjorner)
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--*/
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#include "tactic/bv/bv_bounds_tactic.h"
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#include "tactic/core/ctx_simplify_tactic.h"
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#include "tactic/core/dom_simplify_tactic.h"
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#include "ast/bv_decl_plugin.h"
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#include "ast/ast_pp.h"
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#include <climits>
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static uint64_t uMaxInt(unsigned sz) {
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SASSERT(sz <= 64);
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return ULLONG_MAX >> (64u - sz);
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}
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namespace {
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template<typename T, typename Base>
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struct interval_tpl : public Base {
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T l, h;
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unsigned sz = 0;
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bool tight = true;
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interval_tpl(T const& l, T const& h, unsigned sz, bool tight = false): l(l), h(h), sz(sz), tight(tight) {}
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interval_tpl() {}
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bool invariant() const {
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return
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0 <= l && (l <= Base::bound(sz)) &&
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0 <= h && (h <= Base::bound(sz)) &&
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(!is_wrapped() || l != h + 1);
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}
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bool is_full() const {
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return l == 0 && h == Base::bound(sz);
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}
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bool is_wrapped() const { return l > h; }
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bool is_singleton() const { return l == h; }
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bool operator==(const interval_tpl<T, Base>& b) const {
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SASSERT(sz == b.sz);
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return l == b.l && h == b.h && tight == b.tight;
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}
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bool operator!=(const interval_tpl& b) const { return !(*this == b); }
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bool implies(const interval_tpl<T, Base>& b) const {
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if (b.is_full())
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return true;
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else if (is_full())
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return false;
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else if (is_wrapped())
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// l >= b.l >= b.h >= h
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return b.is_wrapped() && h <= b.h && l >= b.l;
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else if (b.is_wrapped())
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// b.l > b.h >= h >= l
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// h >= l >= b.l > b.h
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return h <= b.h || l >= b.l;
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else
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return l >= b.l && h <= b.h;
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}
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/// return false if intersection is unsat
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bool intersect(const interval_tpl<T, Base>& b, interval_tpl& result) const {
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if (is_full() || *this == b) {
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result = b;
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return true;
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}
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if (b.is_full()) {
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result = *this;
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return true;
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}
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if (is_wrapped()) {
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if (b.is_wrapped()) {
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if (h >= b.l)
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result = b;
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else if (b.h >= l)
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result = *this;
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else
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result = interval_tpl(std::max(l, b.l), std::min(h, b.h), sz);
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}
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else
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return b.intersect(*this, result);
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}
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else if (b.is_wrapped()) {
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// ... b.h ... l ... h ... b.l ..
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if (h < b.l && l > b.h)
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return false;
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// ... l ... b.l ... h ...
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if (h >= b.l && l <= b.h)
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result = b;
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else if (h >= b.l)
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result = interval_tpl(b.l, h, sz);
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else {
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// ... l .. b.h .. h .. b.l ...
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SASSERT(l <= b.h);
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result = interval_tpl(l, std::min(h, b.h), sz);
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}
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} else {
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if (l > b.h || h < b.l)
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return false;
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// 0 .. l.. l' ... h ... h'
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result = interval_tpl(std::max(l, b.l), std::min(h, b.h), sz, tight && b.tight);
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}
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return true;
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}
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/// return false if negation is empty
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bool negate(interval_tpl<T, Base>& result) const {
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if (!tight)
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result = interval_tpl(Base::zero(), Base::bound(sz), sz, true);
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else if (is_full())
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return false;
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else if (l == 0 && Base::bound(sz) == h)
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result = interval_tpl(Base::zero(), Base::bound(sz), sz);
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else if (l == 0)
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result = interval_tpl(h + 1, Base::bound(sz), sz);
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else if (Base::bound(sz) == h)
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result = interval_tpl(Base::zero(), l - 1, sz);
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else
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result = interval_tpl(h + 1, l - 1, sz);
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return true;
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}
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};
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struct rinterval_base {
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static rational bound(unsigned sz) {
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return rational::power_of_two(sz) - 1;
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}
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static rational zero() { return rational::zero(); }
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};
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struct rinterval : public interval_tpl<rational, rinterval_base> {
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rinterval(rational const& l, rational const& h, unsigned sz, bool tight = false) {
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this->l = l; this->h = h; this->sz = sz; this->tight = tight;
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}
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rinterval() { l = 0; h = 0; tight = true; }
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};
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struct iinterval_base {
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static uint64_t bound(unsigned sz) { return uMaxInt(sz); }
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static uint64_t zero() { return 0; }
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};
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struct iinterval : public interval_tpl<uint64_t, iinterval_base> {
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iinterval(uint64_t l, uint64_t h, unsigned sz, bool tight = false) {
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this->l = l; this->h = h; this->sz = sz; this->tight = tight;
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}
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iinterval() { l = 0; h = 0; sz = 0; tight = true; }
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};
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struct interval {
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bool is_small = true;
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iinterval i;
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rinterval r;
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interval() {}
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interval(rational const& l, rational const& h, unsigned sz, bool tight = false) {
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if (sz <= 64) {
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is_small = true;
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i.l = l.get_uint64();
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i.h = h.get_uint64();
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i.tight = tight;
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i.sz = sz;
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}
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else {
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is_small = false;
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r.l = l;
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r.h = h;
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r.tight = tight;
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r.sz = sz;
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}
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}
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unsigned size() const {
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return is_small ? i.sz : r.sz;
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}
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bool negate(interval& result) const {
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result.is_small = is_small;
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if (is_small)
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return i.negate(result.i);
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else
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return r.negate(result.r);
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}
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bool intersect(interval const& b, interval & result) const {
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result.is_small = is_small;
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SASSERT(b.is_small == is_small);
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if (is_small)
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return i.intersect(b.i, result.i);
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else
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return r.intersect(b.r, result.r);
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}
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bool operator==(interval const& other) const {
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SASSERT(is_small == other.is_small);
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return is_small ? i == other.i : r == other.r;
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}
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bool operator!=(interval const& other) const {
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return !(*this == other);
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}
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bool is_singleton() const { return is_small ? i.is_singleton() : r.is_singleton(); }
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bool is_full() const { return is_small ? i.is_full() : r.is_full(); }
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bool tight() const { return is_small ? i.tight : r.tight; }
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bool implies(const interval& b) const {
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SASSERT(is_small == b.is_small);
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return is_small ? i.implies(b.i) : r.implies(b.r);
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}
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rational lo() const { return is_small ? rational(i.l, rational::ui64()) : r.l; }
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rational hi() const { return is_small ? rational(i.h, rational::ui64()) : r.h; }
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};
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std::ostream& operator<<(std::ostream& o, const interval& I) {
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if (I.is_small)
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return o << "[" << I.i.l << ", " << I.i.h << "]";
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else
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return o << "[" << I.r.l << ", " << I.r.h << "]";
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}
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struct undo_bound {
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expr* e = nullptr;
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interval b;
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bool fresh = false;
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undo_bound(expr* e, const interval& b, bool fresh) : e(e), b(b), fresh(fresh) {}
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};
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struct bv_bounds_base {
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typedef obj_map<expr, interval> map;
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typedef obj_map<expr, bool> expr_set;
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typedef obj_map<expr, unsigned> expr_cnt;
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ast_manager& m;
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bv_util m_bv;
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vector<undo_bound> m_scopes;
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svector<expr_set*> m_expr_vars;
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svector<expr_cnt*> m_bound_exprs;
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map m_bound;
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bool m_propagate_eq = false;
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bv_bounds_base(ast_manager& m):m(m), m_bv(m) {}
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virtual ~bv_bounds_base() {
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for (auto* e : m_expr_vars)
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dealloc(e);
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for (auto* b : m_bound_exprs)
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dealloc(b);
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}
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bool is_bound(expr *e, expr*& v, interval& b) const {
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rational r;
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expr *lhs = nullptr, *rhs = nullptr;
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unsigned sz;
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if (m_bv.is_bv_ule(e, lhs, rhs)) {
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if (m_bv.is_numeral(lhs, r, sz)) { // C ule x <=> x uge C
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if (m_bv.is_numeral(rhs))
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return false;
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b = interval(r, rational::power_of_two(sz) - 1, sz, true);
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v = rhs;
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return true;
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}
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if (m_bv.is_numeral(rhs, r, sz)) { // x ule C
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b = interval(rational::zero(), r, sz, true);
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v = lhs;
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return true;
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}
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// TBD: x + s <= x + q
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// x + s <= x
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// x <= x + q
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}
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else if (m_bv.is_bv_sle(e, lhs, rhs)) {
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if (m_bv.is_numeral(lhs, r, sz)) { // C sle x <=> x sge C
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if (m_bv.is_numeral(rhs))
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return false;
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b = interval(r, rational::power_of_two(sz-1) - 1, sz, true);
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v = rhs;
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return true;
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}
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if (m_bv.is_numeral(rhs, r, sz)) { // x sle C
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b = interval(rational::power_of_two(sz-1), r, sz, true);
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v = lhs;
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return true;
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}
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// TBD: other cases for forbidden intervals
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}
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else if (m.is_eq(e, lhs, rhs)) {
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if (m_bv.is_numeral(rhs))
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std::swap(lhs, rhs);
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if (m_bv.is_numeral(rhs))
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return false;
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if (m_bv.is_numeral(lhs, r, sz)) {
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unsigned lo, hi;
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expr* rhs2;
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if (m_bv.is_extract(rhs, lo, hi, rhs2) && r == 0) {
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unsigned sz2 = m_bv.get_bv_size(rhs2);
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if (sz2 - 1 == hi) {
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b = interval(rational::zero(), rational::power_of_two(lo) - 1, sz2, false);
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v = rhs2;
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return true;
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}
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}
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b = interval(r, r, sz, true);
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v = rhs;
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return true;
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}
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}
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return false;
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}
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bool assert_expr_core(expr * t, bool sign) {
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while (m.is_not(t, t))
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sign = !sign;
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interval b;
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expr* t1;
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if (is_bound(t, t1, b)) {
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SASSERT(m_bv.get_bv_size(t1) == b.size());
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SASSERT(!m_bv.is_numeral(t1));
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if (sign && !b.negate(b))
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return false;
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TRACE("bv", tout << (sign?"(not ":"") << mk_pp(t, m) << (sign ? ")" : "") << ": " << mk_pp(t1, m) << " in " << b << "\n";);
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map::obj_map_entry* e = m_bound.find_core(t1);
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if (e) {
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interval& old = e->get_data().m_value;
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interval intr;
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if (!old.intersect(b, intr))
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return false;
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if (old == intr)
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return true;
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m_scopes.push_back(undo_bound(t1, old, false));
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old = intr;
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SASSERT(old.size() == m_bv.get_bv_size(t1));
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}
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else {
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SASSERT(b.size() == m_bv.get_bv_size(t1));
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m_bound.insert(t1, b);
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m_scopes.push_back(undo_bound(t1, interval(), true));
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}
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}
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return true;
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}
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//
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// x + q <= s <=> x not in [s - q + 1, -q[
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// <=> x in [-q, s - q], s != -1
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//
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// x in [lo, hi]
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// q = -lo
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// hi = s + lo => s = hi - lo
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// hi - lo != -1
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//
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expr_ref mk_bound(expr* t, rational const& lo, rational const& hi) {
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sort* s = t->get_sort();
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if (lo == hi + 1)
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return expr_ref(m.mk_true(), m);
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else
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return expr_ref(m_bv.mk_ule(m_bv.mk_bv_add(t, m_bv.mk_numeral(-lo, s)), m_bv.mk_numeral(hi - lo, s)), m);
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}
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bool simplify_core(expr* t, expr_ref& result) {
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expr* t1;
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interval b;
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if (m_bound.find(t, b) && b.is_singleton()) {
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result = m_bv.mk_numeral(b.lo(), m_bv.get_bv_size(t));
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return true;
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}
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if (!m.is_bool(t))
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return false;
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bool sign = false;
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while (m.is_not(t, t))
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sign = !sign;
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if (!is_bound(t, t1, b))
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return false;
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if (sign && b.tight()) {
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sign = false;
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if (!b.negate(b)) {
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result = m.mk_false();
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return true;
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}
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}
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interval ctx, intr;
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result = nullptr;
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if (b.is_full() && b.tight())
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result = m.mk_true();
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else if (!m_bound.find(t1, ctx)) {
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}
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else if (ctx.implies(b))
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result = m.mk_true();
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else if (!b.intersect(ctx, intr))
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result = m.mk_false();
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else if (m_propagate_eq && intr.is_singleton())
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result = m.mk_eq(t1, m_bv.mk_numeral(intr.lo(), t1->get_sort()));
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else if (false && intr != b)
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result = mk_bound(t1, intr.lo(), intr.hi());
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else {
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TRACE("bv", tout << mk_pp(t, m) << " b: " << b << " ctx: " << ctx << " intr " << intr << "\n");
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}
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CTRACE("bv", result, tout << mk_pp(t, m) << " " << b << " (ctx: " << ctx << ") (intr: " << intr << "): " << result << "\n";);
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if (sign && result)
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result = m.mk_not(result);
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return result != nullptr;
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}
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// check if t contains v
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ptr_vector<expr> todo;
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bool contains(expr* t, expr* v) {
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ast_fast_mark1 mark;
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todo.push_back(t);
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while (!todo.empty()) {
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t = todo.back();
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todo.pop_back();
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if (mark.is_marked(t))
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continue;
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if (t == v) {
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todo.reset();
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return true;
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}
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mark.mark(t);
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if (!is_app(t))
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continue;
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app* a = to_app(t);
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todo.append(a->get_num_args(), a->get_args());
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}
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return false;
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}
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bool contains_bound(expr* t) {
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ast_fast_mark1 mark1;
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ast_fast_mark2 mark2;
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todo.push_back(t);
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while (!todo.empty()) {
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t = todo.back();
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todo.pop_back();
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if (mark1.is_marked(t)) {
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continue;
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}
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mark1.mark(t);
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if (!is_app(t)) {
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continue;
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}
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interval b;
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expr* e;
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if (is_bound(t, e, b)) {
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if (mark2.is_marked(e)) {
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todo.reset();
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return true;
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}
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mark2.mark(e);
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if (m_bound.contains(e)) {
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todo.reset();
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return true;
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}
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}
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app* a = to_app(t);
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todo.append(a->get_num_args(), a->get_args());
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}
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return false;
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}
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void pop_core(unsigned num_scopes) {
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TRACE("bv", tout << "pop: " << num_scopes << "\n";);
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if (m_scopes.empty())
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return;
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unsigned target = m_scopes.size() - num_scopes;
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if (target == 0) {
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m_bound.reset();
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m_scopes.reset();
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return;
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}
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for (unsigned i = m_scopes.size(); i-- > target; ) {
|
|
undo_bound& undo = m_scopes[i];
|
|
SASSERT(m_bound.contains(undo.e));
|
|
if (undo.fresh)
|
|
m_bound.erase(undo.e);
|
|
else
|
|
m_bound.insert(undo.e, undo.b);
|
|
}
|
|
m_scopes.shrink(target);
|
|
}
|
|
|
|
};
|
|
|
|
class bv_bounds_simplifier : public ctx_simplify_tactic::simplifier, public bv_bounds_base {
|
|
params_ref m_params;
|
|
|
|
public:
|
|
bv_bounds_simplifier(ast_manager& m, params_ref const& p) : bv_bounds_base(m), m_params(p) {
|
|
updt_params(p);
|
|
}
|
|
|
|
void updt_params(params_ref const & p) override {
|
|
m_propagate_eq = p.get_bool("propagate_eq", false);
|
|
}
|
|
|
|
static void get_param_descrs(param_descrs& r) {
|
|
r.insert("propagate-eq", CPK_BOOL, "propagate equalities from inequalities", "false");
|
|
}
|
|
|
|
~bv_bounds_simplifier() override {}
|
|
|
|
bool assert_expr(expr * t, bool sign) override {
|
|
return assert_expr_core(t, sign);
|
|
}
|
|
|
|
bool simplify(expr* t, expr_ref& result) override {
|
|
return simplify_core(t, result);
|
|
}
|
|
|
|
bool may_simplify(expr* t) override {
|
|
if (m_bv.is_numeral(t))
|
|
return false;
|
|
|
|
while (m.is_not(t, t));
|
|
|
|
for (auto & v : m_bound)
|
|
if (contains(t, v.m_key))
|
|
return true;
|
|
|
|
expr* t1;
|
|
interval b;
|
|
// skip common case: single bound constraint without any context for simplification
|
|
if (is_bound(t, t1, b))
|
|
return b.is_full() || m_bound.contains(t1);
|
|
|
|
return contains_bound(t);
|
|
}
|
|
|
|
void pop(unsigned num_scopes) override {
|
|
pop_core(num_scopes);
|
|
}
|
|
|
|
simplifier * translate(ast_manager & m) override {
|
|
return alloc(bv_bounds_simplifier, m, m_params);
|
|
}
|
|
|
|
unsigned scope_level() const override {
|
|
return m_scopes.size();
|
|
}
|
|
};
|
|
|
|
|
|
class dom_bv_bounds_simplifier : public dom_simplifier, public bv_bounds_base {
|
|
params_ref m_params;
|
|
|
|
public:
|
|
dom_bv_bounds_simplifier(ast_manager& m, params_ref const& p) : bv_bounds_base(m), m_params(p) {
|
|
updt_params(p);
|
|
}
|
|
|
|
~dom_bv_bounds_simplifier() override {
|
|
}
|
|
|
|
void updt_params(params_ref const & p) override {
|
|
m_propagate_eq = p.get_bool("propagate_eq", false);
|
|
}
|
|
|
|
void collect_param_descrs(param_descrs& r) override {
|
|
r.insert("propagate-eq", CPK_BOOL, "propagate equalities from inequalities", "false");
|
|
}
|
|
|
|
bool assert_expr(expr * t, bool sign) override {
|
|
return assert_expr_core(t, sign);
|
|
}
|
|
|
|
void operator()(expr_ref& r) override {
|
|
expr_ref result(m);
|
|
simplify_core(r, result);
|
|
if (result)
|
|
r = result;
|
|
}
|
|
|
|
void pop(unsigned num_scopes) override {
|
|
pop_core(num_scopes);
|
|
}
|
|
|
|
dom_simplifier * translate(ast_manager & m) override {
|
|
return alloc(dom_bv_bounds_simplifier, m, m_params);
|
|
}
|
|
|
|
unsigned scope_level() const override {
|
|
return m_scopes.size();
|
|
}
|
|
};
|
|
|
|
}
|
|
|
|
tactic * mk_bv_bounds_tactic(ast_manager & m, params_ref const & p) {
|
|
return clean(alloc(ctx_simplify_tactic, m, alloc(bv_bounds_simplifier, m, p), p));
|
|
}
|
|
|
|
tactic * mk_dom_bv_bounds_tactic(ast_manager & m, params_ref const & p) {
|
|
return clean(alloc(dom_simplify_tactic, m, alloc(dom_bv_bounds_simplifier, m, p), p));
|
|
}
|